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CROP BREEDING & GENETICS

Mapping of QTL Associated with Maize Weevil Resistance in Tropical Maize

^a Global Maize Program, CIMMYT, Apdo. Postal 6-641, 06600, Mexico DF, Mexico
^b Crop Resource Information Lab., CIMMYT, Apdo. Postal 6-641, 06600, Mexico DF, Mexico

^* Corresponding author (d.bergvinson{at}gmail.com).

The maize weevil (MW), Sitophilus zeamais (Motsch.), is an important pest of stored maize (Zea mays L.) in tropical areas. Quantitative trait loci (QTL) associated with MW resistance were analyzed. A total of 163 F₂ progeny derived from the cross CML290 (susceptible) x Muneng-8128 C0 HC1-18-2-1-1 (resistant), were genotyped with 151 molecular markers. Resistance was evaluated using bioassays on replicated F_2:3 progenies. Grain damage (GD), grain weight losses (GWL), MW susceptibility index (Dobie index [DI]), and numbers of adult progeny (AP) were evaluated on grain from F₂ lines across two environments. Grain hardness and pericarp/grain ratio were evaluated as putative components of resistance. Composite interval mapping was used for QTL analysis. Five QTL dispersed across the genome explained 28% of the phenotypic variance (_p²) and 50% of the genotypic variance (_g²) for GD. Six QTL were detected with effects on GWL and explained 22% of _p² and 47% of _g². Seven QTL (27% _p² and 78% _g²) were identified for DI and three QTL (10% _p² and 23% _g²) for AP. Both parents contributed resistance alleles. Genetic effects were mainly dominant (GD, GWL, and DI) and additive (AP). Quantitative trait loci x environment interaction was significant for 50% of the QTL. Since the identified QTL accounted for less than a third of _p², additional mapping populations are required for mapping MW susceptibility.

Abbreviations: AP, adult progeny • CE, corn earworm • CIM, composite interval mapping • CIMMYT, International Maize and Wheat Improvement Center • cM, centimorgan • DI, Dobie index • ECB, European corn borer • GD, grain damage • GH, grain hardness • GWL, grain weight loss • MAS, marker-assisted selection • MW, maize weevil • P/G, pericarp/grain ratio • QTL, quantitative trait loci • QTL x E, QTL by environment • RFLP, restriction fragment length polymorphism • SCB, sugarcane corn borer • SSR, simple sequence repeat • SWCB, southwestern corn borer